The great cities of the American southwest would not exist if it weren’t for dams. Without the massive federal and state projects to build dams, pumping stations, and aqueducts (most of them completed 50 to 100 years ago), more than 60 million Americans would be living somewhere else. Without dams to capture and store millions of acre-feet of rainfall every year, and aqueducts to transport that water to thirsty metropolitan customers, the land these cities sit upon would be uninhabitable desert.

Such is the conundrum facing environmentalists that want to set these rivers free. Without dams, crops wither and people die of thirst. Without dams, devastating floods would tear through towns and cities every time there’s a big storm. Without hydroelectric power from dams, 18 percent of the in-state generated electricity Californians consume would be gone. You can’t just rip them all out. You would destroy a civilization.

But because of dams, fish habitat is lost, and aquatic species can become endangered or go extinct. Because of dams, precious sediment is prevented from running downstream to nurture estuaries and restore beaches. Because of dams, the natural cycle of rivers is disrupted: the cleansing pulse of spring that calls the migratory salmon to come back from the ocean, the dry trickles of summer when these anadromous species fight their way upstream to the cool and perennial headwaters to spawn, the next season’s rains that return newborn fingerlings to the ocean.

There’s often an aesthetic price to pay as well when dams are built. Perhaps the most notable among them is the Hetch Hetchy Reservoir, inundating a deep, granite-walled valley once considered a rival in beauty to neighboring Yosemite, less than 20 miles away. Notwithstanding the dividends the ecosystems of this once pristine valley paid to wildlife, its breathtaking splendor inspired human visitors. In describing the Hetch Hetchy Valley, the great naturalist and writer John Muir said, “I have always called it the Tuolumne Yosemite, for it is a wonderfully exact counterpart of the great Yosemite, not only in its crystal river and sublime rocks and waterfalls, but in the gardens, groves, and meadows of its flower park-like floor.”

When we attempt to assess the pros and cons of dams and dam removal in the western United States today, Hetch Hetchy is a good focal point. Situated at 3,900 feet above sea level and gathering runoff from the 492-square-mile watershed of the upper Tuolumne River, the 430-foot-tall O’Shaughnessy Dam can hold up to 360,000 acre-feet in what was once the Hetch Hetchy Valley. This water is transported 160 miles through pipes and tunnels, generating 385 constant megawatts of hydroelectricity along the way, finally dumping nearly 300,000 acre-feet per year into the Crystal Springs Reservoir, which is located 238 feet above sea level in the Santa Cruz Mountains, just south of San Francisco.

A sensible environmentalism is one that recognizes that environmentalism must involve trade-offs. If you’re going to get rid of dams because they are an abomination to nature — the environmentalist position — you ought to be starting with Hetch Hetchy. Because of that dam, residents of San Francisco and the upper peninsula cities clustered along the bay are recipients of the most reliable, purest water in California. It only takes five feet of snow in the High Sierra to guarantee San Franciscans their full allotment of water and electricity from Hetch Hetchy, a quantity that is achieved in all but the most severe drought years. Progressive environmentalists in San Francisco might talk a good game about removing dams in other areas, but they are curiously accepting of the massive one that benefits them.

The reality in the American west is that every source of water is imperiled. In an average year, California’s farmers rely on about 30 million acre-feet per year to irrigate not quite 10 million acres of crops (15,600 square miles), and urban water agencies require another 8 million acre-feet per year. Diversions to maintain ecosystem health require at least another 30 million acre-feet.

But groundwater aquifers, which have supplied over 18 million acre-feet per year, are overtapped and will require years of reduced pumping if they are to recover. The Colorado River aqueduct, delivering 5 million acre-feet per year to California, depends on water stored in Lake Powell and Lake Mead, both of which are at historic lows. Eithr Californians are going to develop new sources of fresh water by investing in water-supply infrastructure, or they are going to have to take millions of acres of farmland out of production and subject their residents to unprecedented restrictions on water use. They face a deficit of at least 5 million acre-feet per year.

Which brings us back to California’s dams and reservoirs.

Most of California’s reservoirs are in-stream, which means the reservoir is behind a dam blocking a river, controlling 100 percent of its runoff. In-stream reservoirs cannot be used to store water from early season storms, such as the deluge that fell in December 2021. If California’s in-stream reservoirs are filled early in the rainy season, should a late-season storm hit the state, no storage capacity would be left to control the runoff and prevent flooding. But during droughts, when an adequate Sierra snowpack fails to develop in order to deliver snowmelt well into the summer months, and no late-season rainstorms inundate the state, summer arrives and the reservoirs are empty.

All of this raises the question: If in-stream dams are to be removed to restore aquatic habitat, why shouldn’t development of new water sources, more than offsetting the lost water supply, be part of the project? Why consider these projects in isolation, instead of connecting them? Off-stream reservoirs, which are situated in arid valleys where water is pumped into them from adjacent rivers during storms, can store millions of acre-feet without disrupting important rivers. Wastewater treatment can reuse effluent that is imported into California’s coastal cities at great cost, only to be discharged into the Pacific Ocean after only one use. Ocean desalination finds an ideal venue on the California coast, yet its potential has barely been tapped. The answer, very often, is the refusal to consider realistic trade-offs.

One of the principal environmentalist groups working to facilitate dam removal is American Rivers, headquartered in Washington, D.C., with affiliates and partners all over the U.S. From a review of the organization’s map of dams removed through 2021, two striking facts emerge: A lot of dams have been removed, and almost all of them have been small dams.

When speaking with Serena McClain, the National Dam Removal Practice Lead for American Rivers, it was clear that her organization didn’t expect to remove any of the 240 very large dams that account for 60 percent of California’s total reservoir storage capacity, or, for that matter, many of the more than 1,200 remaining smaller storage dams. “We don’t have a hit list,” she said, “and we don’t want to remove all dams. We want to find the best solution that helps all parties. The majority of dams are small to midscale. Only 20 percent of the dams that have been removed are in the Army Corps of Engineers’ national inventory of dams, the rest are so small they don’t even qualify.”

“Small” is a relative concept, of course. While the political and financial cost, not to mention the loss of capacity, suggests that it is all but impossible to remove large dams with reservoirs that store hundreds of thousands of acre-feet, some medium-sized dams with reservoirs under 100,000 acre-feet of capacity are definitely targeted. Some of these dams are completely silted up, and their removal faces no opposition.

For example, Matilija Dam in Southern California, 168 feet tall and 620 feet long, built in 1947, originally created a reservoir with a storage capacity of 7,000 acre-feet, but now it is almost completely filled up with silt. Dredging to remove the silt is not cost-effective to recover only 7,000 acre-feet of storage. No longer viable for a reservoir, the dam blocks southern California steelhead-trout migration on the Ventura River, preventing passage to over 50 percent of the primary spawning, rearing, and forging habitat of the river system. The dam also prevents downstream transport of nearly 8 million cubic yards of sediment necessary to maintain the lower-river ecosystem, estuary, and beaches of southern California.

Also in southern California, Rindge Dam is a 100-feet-high concrete dam built in Malibu Creek in 1926. By 1940 the reservoir was filled with sediment, and attempts to remove the sediment were unsuccessful. Removal will allow steelhead trout to access 18 miles of high-quality spawning and rearing habitat in the Malibu Creek watershed.

In northern California, Scott Dam and Cape Horn Dam, on the Eel River, are two dams that make up the Potter Valley Project. The Eel River is the third-largest watershed in California, and these dams block salmon and steelhead from reaching the Eel River’s headwaters. But this project is not entirely uncontroversial. Scott Dam, with Lake Pillsbury behind it, has a storage capacity of 74,000 acre-feet. Cape Horn Dam, while small, creates a forebay to divert 70,000 acre-feet per year down into the Potter Valley, to help feed the headwaters of the Russian River. A powerhouse, exploiting the 650-foot drop in elevation, generates 9.5 megawatts whenever water is being diverted into Potter Valley.

Jeffery Mount, a water expert at the Public Policy Institute of California, pointed out that the removal proposal includes retaining the capacity to divert water to consumers on the Russian River, which is of great concern to farmers and water agencies downstream. He told me the only people who may strenuously object to losing Scott Dam are the property owners that enjoy the amenities of Lake Pillsbury, which will no longer exist if the dam is removed.

Mount’s comment, and the Potter Valley Project’s legacy of providing water, power, and recreational amenities, points to a core controversy surrounding dam removal, which is how to define beneficial use. One hundred years earlier, during public debate over whether to build the O’Shaughnessy Dam, proponents pointed to these same public benefits of water, power, and recreation. More recently, the California Water Commission used the concept of public benefit, in which it emphasized benefits to ecosystems (a significantly narrower definition with little room, except indirectly, for the inclusion of human welfare in the equation) as a way to deny adequate funding for some of the dam projects approved by California’s voters in 2014.

The complexity of these issues, the unresolved scientific debate over many of them, and the necessarily subjective choice that has to be made over whether to prioritize human benefit or benefit to wildlife, guarantees that every dam-removal proposal will generate public controversy, but only in proportion to how big the dam facing removal is. A few landowners on the shores of a small and remote lake have almost no political clout.

Put another way, the weight and momentum of the institutional forces that favor removal, which focus on one dam after another, will always overcome local resistance if the dam and its reservoir isn’t very big. These institutional forces include federal and state bureaucrats with an ideological bias against dams, powerful environmental activist groups and the think tanks aligned with them, most sport fishing and hunting organizations, and Native American tribes as well as, in some cases, utilities that want to be rid of silted-up reservoirs with obsolete powerhouses.

Which brings us to four dams on the Klamath River: J.C. Boyle, Copco No. 1, Copco No. 2, and Iron Gate dams. The reservoirs behind these small-to-medium-sized dams have a combined storage capacity of over 140,000 acre-feet. All are scheduled for removal, and demolition could begin as soon as next year.

One of the biggest rivers in the western United States, but known to relatively few, is the mighty Klamath, encompassing a massive 16,000-square-mile watershed that straddles southern Oregon and California’s far north. With headwaters in the Cascade Mountains of Oregon, the Klamath bends its way west into California through deep canyons, finding the ocean in an estuary roughly 30 miles south of the Oregon border.

The Klamath is distinguished not only by its vast extent and unique topography, but by its importance to salmon populations. Until you reach the Columbia River over 400 miles to the north, the Klamath and its tributaries offer the largest spawning habitat for salmon in North America.

Meanwhile, the powerhouses on these four dams have the capacity to generate up to 160 megawatts, which goes a long way in the sparsely populated counties of northern California and southern Oregon. More controversial than the loss of hydroelectric capacity, however, is concern among farmers over what is going to happen upriver once these four dams are removed. Because there’s one more reservoir on the Klamath, upstream from the four targeted for removal.

When the Link River Dam was built at the southern end of Upper Klamath Lake in 1921, the intention was to provide water storage for irrigation to what is some of the richest farmland on earth. By the 1900s, over 200,000 acres were planted with alfalfa, barley, garlic, horseradish, onions, potatoes, sugar beets, and wheat. And then came the water wars.

In March 2020, federal water allocations from Upper Klamath Lake to farmers in Klamath County, Ore., were cut from the historical norm of 350,000 acre-feet down to 140,000 acre-feet, and then in May 2020, after the farmers had already invested in crops for that year, the allocation was cut further, to 50,000 acre-feet. After a 30-mile-long convoy of rural dissidents descended on Klamath Falls to protest the cutback, the 140,000-acre-foot allocation was restored. But then in 2021, for the first time in 120 years, the Bureau of Reclamation — which has the authority to manage water resources in the United States — said the farmers would get a zero allocation; after more protests the farmers ended up with 50,000 acre-feet. In 2022, after another initial zero allocation, the farmers got 80,000 acre-feet.

Rural communities and farm interests throughout the American West view every dam removal as a growing and existential threat. Not necessarily because removal of the dams currently slated for removal are going to deprive them of irrigation for their crops, but because of the mentality of the agencies that control the water and concern for what new dam removals and other restrictions come next.

Is it even “science” that compels the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and the Bureau of Reclamation to maintain that more water in the Klamath River, year round, improves the survivability of salmon? Don’t the parasites that attack salmon die when rivers naturally run nearly dry in the summer? Doesn’t science rely on testing various hypotheses, rather than adhering to one theory — more water in the river, all summer long — despite no evidence that it’s helping restore fish populations? And how could those summer flows ever be maintained, anyway, without dams?

In Idaho, environmentalists claim that four dams on the lower Snake River — Ice Harbor, Lower Monumental, Little Goose, and Lower Granite — must be removed as part of any recovery plan for endangered salmon and steelhead. Plans are moving forward to remove them but are running into opposition. These are big dams; their four reservoirs have a combined storage capacity of over 1.6 million acre-feet. Replacing the irrigation infrastructure, offsetting the losses in waterway transportation, and replacing the more than 1,000 megawatts of hydroelectricity would cost an estimated $30 billion or more.

The biggest threat to water supply in the American West isn’t dam removal, which, despite what I have written above, is unlikely to spiral out of control, nor is it terribly objectionable to get rid of small and obsolete dams. The threat is everything that surrounds the dam-removal movement, which is a symptom of a far wider set of problems, such as that posed by powerful bureaucrats who believe that conservation, and nothing else, will resolve the challenge of water scarcity.

Then there are the experts who claim, despite evidence to the contrary, that maintaining strong year-round flows in rivers that historically used to run nearly dry in summer will somehow benefit fish. And let’s not forget the climate-change zealots who think hydropower, along with fossil fuels, can all be replaced with nothing more than wind, solar, and battery farms. Even the possible (partial) solution represented by nuclear power is rejected by many of the eco-activists involved in climate-change campaigning.

Perhaps most of all, the threat posed by the prospect of removing bigger dams, such as the ones on the Snake River, is the failure of proponents of removal to support major new water-supply infrastructure, including new off-stream reservoirs. If the proponents of dam removal would simultaneously support practical new infrastructure solutions, then rewilding America’s rivers could happen without impoverishing the farms and cities that depend on water.

There is naïveté, and also nihilism, in fighting to remove the building blocks of civilization without facing the realities of energy and water economics. Off-stream reservoirs, wastewater recycling, spreading basins to percolate floodwater into underground aquifers, desalination, and an all-of-the-above approach to energy development — more of these infrastructure investments become necessary when dams are removed from rivers. That environmental activists fail to understand the consequences of their actions will only mean disaster if they continue to get their way.

This article originally appeared in the National Review.